<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link rel="stylesheet" href="./css/index.css">
  <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>

  <title>记事本</title>
</head>

<body>
  <!--主题区域  -->
  <section id="app">
    <!-- 输入框 -->
    <header class="header">
      <h1>小黑记事本</h1>
      <input v-model="todoName" placeholder="请输入标题" class="new-todo" />
      <button @click="add" class="add">添加任务</button>
    </header>
    <!-- 任务列表 -->
    <section class="main">
      <ul class="todo-list">
        <li class="todo" v-for="(item,index) in list" :key="item.id">
          <div class="view">
            <span class="index">{{ index + 1 }}</span><label>{{ item.name }}</label>
            <button class="destroy" @click="del(item.id)"></button>
          </div>
        </li>
      </ul>
    </section>
    <!-- 统计和清空 -->
    <footer class="footer" v-show="list.length > 0">
      <!-- 统计 -->
      <span class="todo-count">合计：<strong>{{ list.length }}</strong></span>
      <button class="clear-completed" @click="clear">清空任务</button>
    </footer>

  </section>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        list: [
          { id: '1', name: '听音乐' },
          { id: '2', name: '看电影' },
          { id: '3', name: '不想明天的事情' }
        ]
      },
      methods: {
        del(id) {
          // console.log(id) => filter 保留所有不等于该 id 的项
          console.log(id)
          this.list = this.list.filter(item => item.id !== id)
        },
        add() {
          if (this.todoName.trim() === '') {
            alert('请输入任务名称')
            return
          }
          this.list.unshift({ id: Date.now(), name: this.todoName })
          this.todoName = ''
        },
        clear() {
          this.list = []
        }
      }
    })
  </script>


</body>

</html>